Human intervertbral discs generally serve two functions, they cushion and allow movement between two adjacent vertebrae. The cushioning is performed by a gel-like material, which forms the inner part of the discs. These discs are known to deteriorate with age, injury, or disease. When discs are damaged or diseased, the mobility of the subject is often impaired and great pain may result from movement. Damaged discs may also place pressure on the spinal column, causing additional pain.
To relieve the pain associated with disc injury and disease, it has been known to remove the diseased or damaged disc from the intervertebral space, and fuse or otherwise join the adjacent vertebrae that define the intervertebral space. Fusion is often desirable because it serves to fix the vertebral bodies together to prevent movement and maintain the space originally occupied by the intervertebral disc.
Interbody spacers are commonly used to promote fusion in an intervertebral disc between two vertebrae. Common surgical approaches to the disc require a linear “line-of-sight” insertion path LIP (See FIG. 1) that is in-plane with the disc to be fused, in order to accommodate the instruments to prepare the disc space and the linear delivery of the interbody spacer into the disc space.
Traditionally, surgical techniques involved a posterior or anterior approach through the subject to the desired intervertebral disc space. However, the posterior and anterior approaches require careful measures to be taken to avoid vascular tissues along the insertion path. Failure to do so can result in the formation of scar tissue on the vascular tissues. As a result of this and other difficulties with posterior and anterior approaches, a new lateral approach technique was developed.
The new lateral approach to the spine, which is gaining popularity for fusion procedures, allows the surgeon to gain access to the desired intervertebral disc space from the patient's lateral side. The lateral approach generally allows a more complete preparation of the disc space, including a more thorough and complete removal of the original disc material, compared to a posterior approach. A lateral approach also limits access-related surgical trauma and exposure to certain neurological, vascular and other structures while surgically accessing the disc space. Additionally, this improved access allows a larger interbody spacer to be inserted. However, a limitation of the lateral approach is that it is difficult to access the commonly-pathologic L5-S1 lumbar disc due to the patient's iliac crest obstructing the line-of-sight surgical approach. Accessing the L4-L5 space can also prove difficult using a lateral, linear (or line-of-sight) approach.